Medical leaders from around the UK have implored junior doctors in England and the Department of Health to "step back from the brink" and return to negotiations.
The Academy of Medical Royal Colleges said the bitter dispute was "extremely damaging".
Strike action has been planned for April which will see junior doctors walk out for the first time in the history of the NHS.
In previous strike action medics have still provided emergency care. But strikes planned for April 26 and April 27 will see the full withdrawal of labour by junior doctors - everyone up to consultant level - between the hours of 8am and 5pm on both days.
A statement backed by the presidents of all of the medical royal colleges across the UK urged the British Medical Association to suspend plans for the full walkout.
It also called on Health Secretary Jeremy Hunt to pause plans to impose the new contract on junior doctors.
"This is a time of unprecedented crisis for the NHS," the statement says.
"With this in mind and in the spirit of placing patient welfare first and foremost we are writing in response to the escalation of the junior doctor's dispute in England.
"We call on both sides in the dispute to step back from the brink by suspending imposition of the contract and the all-out strike and urge a return to negotiations.
"We believe that this is essential if the current impasse is to be broken and progress made in resolving this extremely damaging stand-off for the benefit of all NHS stakeholders, particularly our patients and trainees."
There will also be a 48-hour strike starting at 8am on Wednesday April 6, with junior doctors providing emergency care only.
Junior doctors are objecting to a new contract in England.
The major sticking point in the dispute has been over weekend pay and whether Saturdays should attract extra "unsocial" payments.
Currently, 7pm to 7am Monday to Friday and the whole of Saturday and Sunday attract a premium rate of pay for junior doctors.
The Government wanted the Saturday day shift to be paid at a normal rate in return for a hike in basic pay.
Talks over the new contract broke down earlier this year and in February the Government announced that it would be imposing the contract from this summer.
Heidi Alexander, Labour's shadow health secretary, said: "Jeremy Hunt must start listening to the growing chorus of medical and patient voices who are urging him to think again.
"Patients must always come first and it is time the Government accepted responsibility for their shambolic handling of these negotiations and returned to talks."
A Department of Health spokeswoman said: "The escalation of strike action by the BMA will inevitably put patients in harm's way and, as the Academy of Medical Royal Colleges has said, would be an unprecedented crisis for the NHS.
"If the BMA had agreed to negotiate on Saturday pay, as they promised to do through Acas in November, we'd have a negotiated agreement by now - instead, we had no choice but to proceed with proposals recommended and supported by NHS leaders - which were 90% agreed with the BMA."